carbon pencils, arranged thus [Symbol] (except that the two v's are
not in the same plane, but in planes at right angles to each other).
The spark crosses the space between the points of the v's, and
arrangements are made for keeping the two points at the right distance
from each other, and also for keeping the ends of the two pencils which
form each point in their proper position. If the current is from any
cause interrupted, an automatic arrangement is adopted to allow the
current to pass to the other lamps in the same circuit. There are
six lamps in circuit at the 'Times' office; and M. Rapieff has
exhibited as many as ten. The advantages claimed for this
light are the following:--'First, its production by any description
of dynamo-electric machine with either alternating or continuous
currents; secondly, great diversibility and complete independence
of the several lights, and long duration without change of carbons;
and lastly, the extreme facility with which any ordinary workman or
servant can renew the carbons when necessary, without extinguishing
the lights.' The last-named advantage results, it need hardly perhaps
be said, from the use of two carbons to form each point. One can be
removed, the other remaining to keep the voltaic arc intact until a
new carbon has been substituted for its fellow; then it in turn can be
replaced by a new carbon, the new carbon already inserted keeping the
voltaic arc intact.
The six lamps at the 'Times' office thoroughly illuminate the room, and
give light for working the eight Walter presses used in printing the
paper. The light has been thus used since the middle of last October,
and it is said that other rooms in the building are shortly to be
illuminated in the same manner. 'Each lamp is enclosed in an opal globe
of about four inches in diameter, and so little heat is given off, that
the hand can be placed on the globe without inconvenience, even after
the light has been burning for some time.'
In the Wallace lamp there are two horizontal plates of carbon, about
nine inches in diameter, instead of mere carbon points. When the
current is passing, these carbon plates are separated by a suitable
small distance which remains unchanged. The electric arc, being started
at the point along the edge of the carbons where there is least
resistance to the passage of the current, gradually passes along the
edge of the carbons as combustion goes on, changing the position of
the place of nearest approach and consequently of least resistance.
The light will thus burn for many hours (even for a hundred with large
carbon plates), and any number of lights up to ten can be worked from
the machine. The objection to the Wallace lamp is, that the light does
not remain at one point, but travels along the whole extent of the
carbons. It will not be easy to design a glass shade which will be
suitable for a light thus changing in position.
The Werdermann regulator is on an entirely new plan; but it has not yet
been submitted to the test of practical working outside the laboratory.
The positive carbon, which is lowest, ends in a sharp point, which
strangely enough retains its figure, while the carbon burns away at
the rate of about two inches per hour. The negative carbon is a block
having its under side, against which the positive carbon presses,
slightly convex. The positive carbon is pressed steadily against the
negative by the action of a weight. The increased resistance to the
passage of the current, at the sharp point of the positive carbon,
generates sufficient heat to produce a powerful light. The light
resembles a steadily radiant star, but 'with all its softness and
purity of tint, it is so intense, that adjacent gas-flames are thrown
on the wall as transparent shadows.' The light will last for fifteen
hours without attention, the positive carbon rod being used in lengths
of three feet. The carbon block hardly undergoes any change. When the
lamp has been burning a long time, a slight depression can be seen
at the place where the positive carbon touches it, but by shifting
the carbon in its holder this is easily remedied. Mr. Werdermann
lately exhibited a row of ten small lamps burning side by side at the
same time. 'The two wires from the machine,' says Mr. Hepworth, were
carried one on either side of this row of lamps, branch wires being led
from them for the service of each lamp. Mr. Werdermann says that his
perfected lamps will be furnished with keys, by which the current can
be turned on or off, as in the case of gas. We may say in fact, that
in the nature of its connections and various arrangements, it ("the
Werdermann lamp") most nearly comes up in convenience to the use of
gas.'
We do not yet know certainly what arrangement Mr. Edison employs to
obtain the light of which so much has been heard. It is asserted that
his light is obtained from the incandescence of an alloy of iridium and
platinum, which will bear without fusion a heat[26] of 5,000 degrees
Fahrenheit. It would be unsafe, however, to assume that this account is
trustworthy, or to infer (as we might in the case of almost any other
inventor), that such being the nature of his plan, it could lead to no
result of practical value. As has been well remarked by a contemporary
writer, whatever Edison's invention may be, 'it is certain to be
something to command respect, even if it does not quite come up to the
glowing accounts which have reached us in advance.'
The following passage from one of these accounts, which appeared in the
'New York Herald,' will be read with interest, and may be accepted as
trustworthy so far as it goes. 'The writer last night saw the invention
in operation in Mr. Edison's laboratory. The inventor was deep in
experimental researches. What he called the apparatus consisted of a
small metal stand placed on the table. Surrounding the light was a
small glass globe. Near by was a gas jet burning low. The Professor
looked up from his work, to greet the reporter, and in reply to a
request to view the invention, waved his hand towards the light, with
the exclamation, "There she is!" The illumination was such as would
come from a brilliant gas jet surrounded with ground glass, only that
the light was clearer and more brilliant. "Now I extinguish it and
light the gas, and you can see the difference," said Mr. Edison, and
he touched the spring. Instantly all was darkness. Then he turned on
the gas. The difference was quite perceptible. The light from the gas
appeared in comparison tinted with yellow. In a moment, however, the
eye had become accustomed to it, and the yellowish tint disappeared.
Then the Professor turned on the electric light, giving the writer the
opportunity of seeing both, side by side. The electric light seemed
much softer; a continuous view of it for three minutes did not pain
the eye; whereas looking at the gas for the same length of time caused
some little pain and confusion of sight. One of the noticeable features
of the light, when fully turned on, was that all the colours could
be distinguished as readily as by sunlight. "When do you expect to
have the invention completed, Mr. Edison?" asked the reporter. "The
substance of it is all right now," he answered, putting the apparatus
away and turning on the gas. "But there are the usual little details
that must be attended to before it goes to the people. For instance, we
have got to devise some arrangement for registering a sort of meter,
and again, there are several different forms that we are experimenting
on now, in order to select the best." "Are the lights to be all of the
same degree of brilliancy?" asked the reporter. "All the same!" "Have
you come across any serious difficulties in it as yet?" "Well, no,"
replied the inventor, "and that's what worries me, for in the telephone
I found about a thousand;[27] and so in the quadruplex. I worked on
both over two years before I overcame them."'
Other methods, as the Sawyer-Man system, and the Brush system, need not
at present detain us, as little is certainly known respecting them. In
the former it is said that the light is obtained from an incandescent
carbon pencil, within a space containing nitrogen and no oxygen, so
that there is no combustion. In the latter the carbon points are placed
as in the ordinary electric lamp, but are so suspended in the clasp of
a regulator, that they burn 14 inches of carbon without adjustment, the
carbons lasting eight hours, and producing a flood of intense white
light, estimated as equivalent to 3,000 candles.
I have little space to consider the cost of electric lighting, even
if the question were one which could be suitably dealt with in these
pages. Opinions are very much divided as to the relative cost of
lighting by gas and by electricity; but the balance of opinion seem to
be in favour of the belief that in America and France certainly, and
probably in this country, where gas is cheap, electric lighting will
on the whole be as cheap as lighting by gas. It should be noticed,
in making a comparison between this country and others in which coal
is dearer, that the cheapness of coal here, though favourable in the
main to gas illumination, is also favourable, though in less degree
(relatively) to electric lighting. Machines for generating electricity
can be worked more cheaply here than in America. Nay, it has even
been found advantageous in some cases to use a gas engine to generate
electricity. Thus Mr. Van der Weyde used an Otto gas engine driven
at the cost of 6_d._ an hour for gas, to produce the light which he
exhibited publicly on the night of November 9. So that the cheapness of
gas may make the electric light cheaper. Then it is to be remembered
that important though the question of cost is, it is far from being
all-important. The advantages of electric lighting for many purposes,
as in public libraries, in cases where many persons work together
under conditions rendering the vitiation of the air by gas lighting
exceedingly mischievous, and in cases where the recognition of delicate
differences of tint or texture is essential, must far more than
compensate for some slight difference in cost. The possibility (shown
by actual experience to be real) of employing natural sources of power
to drive machines for generating electricity, is another interesting
element of the subject, but could not be properly dealt with save in
greater space than this here available.
FOOTNOTES:
[Footnote 23: It is supposed by many, that when the spark is long
enough we can note the direction in which it travels; and observations
of the motion of lightning from the earth to the cloud have been
collected, as showing that the usually observed direction of the flash
is sometimes reversed. In reality, no one has ever seen a lightning
flash travel either one way or the other. If the attention is fixed
on the storm cloud, as usual when a lightning storm is watched, every
flash appears to pass from the cloud to the earth. If, on the contrary,
at the moment when the attention is fixed on some terrestrial object
the lightning flashes near that particular object, the flash will seem
to pass from the object to the cloud. In either case the motion is
apparent only. If there is motion at all, the passage of the electric
spark occupies less than the 100,000th part of a second, and of course
it is utterly impossible that any eye could tell at which end of its
track the flash first appeared. In every case the flash seems to travel
from the end to which attention was more nearly directed. The apparent
motion corresponds to the chance direction of the eye.]
[Footnote 24: The extremity of the wire connected with the metal least
affected by the acid solution is called the positive pole, that of the
wire connected with the metal most affected by the solution is called
the negative pole.]
[Footnote 25: So called, though in reality the best magnets gradually
lose force.]
[Footnote 26: My occasional use of the word 'heat' where in scientific
writing 'temperature' would be the word used, has exposed me to
peevish, not to say petulant comments from Professor P.G. Tait, who
has denounced half the mathematical world for using the word 'force,'
in the sense in which Newton used it, and has spoken of an eminent
physicist as one deserving universal execration and opprobrium for
not explaining, when speaking of work done against gravity, that
terrestrial gravity was meant, and not gravity on the sun, or Jupiter,
or Mars, or anywhere in the heavens above or in the earth beneath,
but only at the earth's surface. Where there is no risk of confusion,
the word 'heat' may be used either to signify temperature, as when
in ordinary speech and writing we talk of blood-heat, fever-heat,
summer-heat, and so forth. Science, indeed, very properly forbids
the use of the word in any sense save one. But outside the pages of
scientific treatises, there is no inaccuracy in using a word in a sense
popularly attributed to it, when no mistake can possibly arise. No one
can suppose, when I speak of a heat of so many degrees Fahrenheit or
Centigrade, that I mean anything but such and such a degree of heat,
any more than if I spoke of the intense heat of that _savant entêté_,
Professor P.G. Tait, any one would imagine that I referred to his
calorific condition.]
[Footnote 27: The comments made by one of Mr. Edison's assistants
on this point are interesting and instructive. 'Mr. Batchelor, the
Professor's assistant, who here joined in the conversation,' proceeds
the report of the _Herald_, 'said, "Many a time Mr. Edison sat down
almost on the point of giving up the telephone as a lost job; but at
the last moment, he would see light." "Of all things that we have
discovered, this is about the simplest," continued Mr. Edison, "and the
public will say so when it is explained. We have got it pretty well
advanced now, but there are some few improvements I have in my mind.
You see, it has got to be so fixed that it cannot get out of order.
Suppose when one light only is employed it got out of order once a
year, where two were used it would get out of order twice a year, and
where a thousand were used you can see there would be much trouble in
looking after them. Therefore, when the light leaves the laboratory, I
want it to be in such a shape that it cannot get out of order at all,
except of course by some accident."']
PRINTED BY
SPOTTISWOODE AND CO. LTD., NEW-STREET SQUARE
LONDON
Trascribers Note:
Original spelling has been retained.
End of Project Gutenberg's Rough Ways Made Smooth, by Richard A. Proctor